If more people were armed, Donald J. Trump says at rallies, mass shootings like those in Paris and San Bernardino, Calif., would be less deadly.

If you have a permit to carry a concealed weapon, he wants to make it valid in all 50 states, as simple as a driver’s license.

And Mr. Trump himself has a permit to carry a concealed handgun, which he is not shy about mentioning. “Somebody attacks me, oh, they’re gonna be shocked,” he warned last year.

Mr. Trump, who promises to “totally protect” the Second Amendment, is scheduled to speak on Friday at the annual convention of the National Rifle Association, on the cusp of a general election in which gun issues are expected to be more prominent than in recent presidential races. His address should signal how far he is likely to go in pressing gun rights to energize the Republican base in the fall campaign.

Whereas President Obama soft-pedaled gun control in both his national runs, Hillary Clinton, the likely Democratic nominee, is signaling a greater appetite to clash with Mr. Trump on the issue.

In a Twitter message last week, Mrs. Clinton said that Mr. Trump, the presumptive Republican nominee, would force schools “to allow guns in classrooms on his first day in office.”

FACT: Donald Trump would force schools to allow guns in classrooms on his first day in office. https://t.co/Y1YSjDDUXC

“This issue is at a tipping point,” said Dan Gross, the president of the Brady Campaign to Prevent Gun Violence, citing Mrs. Clinton’s politically effective framing of gun issues that put Senator Bernie Sanders of Vermont on the defensive in the Democratic primary campaign. “You’re going to hear about it as differentiator for the first time in decades” in the general election, Mr. Gross said.

Mrs. Clinton’s appearances in black churches, where she cited the grim statistics of gun violence and surrounded herself with families of victims, helped her win crucial African-American voters. She relentlessly criticized Mr. Sanders for his votes against gun control in the Senate.

On the other hand, Mrs. Clinton avoided speaking about gun control in rural white regions of Ohio, Pennsylvania and Kentucky, whose blue-collar voters will be desperately fought for by any Democratic nominee against Mr. Trump. A disparaging comment by Mr. Obama in 2008, who said that these voters cling to guns and religion, did much damage.

As Mrs. Clinton turns to the general election, she plans to highlight the issue in swing districts like Northern Virginia and the Philadelphia suburbs, a campaign official said, where changing demographics are tipping support for gun control, especially among women.

Mr. Trump’s naming of 11 potential Supreme Court justices on Wednesday seemed no coincidence: On the eve of the N.R.A.’s meeting, the group’s concern for the court’s conservative tilt is likely to outweigh any hesitations about Mr. Trump’s reversal from earlier liberal positions on gun control.

A statement on gun rights was one of the first detailed policy papers Mr. Trump issued last year after announcing his candidacy.

He accused Mrs. Clinton this month of seeking to “abolish the Second Amendment.” And just as he argues that casualties from the terrorist attacks in Paris last year would have been lower if civilians had been armed, he has proposed abolishing gun-free zones at military bases and at schools.

“I will get rid of gun-free zones on schools, and — you have to — and on military bases,” Mr. Trump said on the campaign trail in January. “My first day, it gets signed, O.K.? My first day. There’s no more gun-free zones.”

A federal law from the 1990s established gun-free school zones. It could not be reversed by executive order, as Mr. Trump seems to imply. (His campaign did not respond to a request for comment about his gun policies.)

“Trump would not be able to eliminate gun-free zones by executive order,” said Adam Winkler, a law professor at the University of California, Los Angeles, and an expert on the Second Amendment. “That law can only be repealed by Congress.”

Mr. Trump opposes almost all recent actions aimed at reducing gun violence proposed by Mr. Obama and Democrats in Congress, who have sought gun regulations after horrific shootings in recent years. Each has failed in the face of Republican opposition.

The measures included expanding background checks to people buying firearms at gun shows and online; limiting the capacity of magazines; and banning assault weapons. “Gun and magazine bans are a total failure,” Mr. Trump wrote in his position paper. “The government has no business dictating what types of firearms good, honest people are allowed to own.”

Those positions represent a reversal from where he stood about 15 years ago when he first contemplated a run for president. In a 2000 book, Mr. Trump supported a ban on assault weapons and a “slightly longer waiting period to purchase a gun.”

He also criticized the power of the gun lobby. “The Republicans walk the N.R.A. line and refuse even limited restrictions,” he wrote.

Bob Barr, an N.R.A. board member, said that despite Mr. Trump’s inconsistencies, he was preferable to Mrs. Clinton, who has said that a 2008 Supreme Court ruling overturning a handgun ban in Washington was wrongly decided.

“We’re all very familiar with the fact Mr. Trump does change his positions over time, sometimes over a very short period of time,” said Mr. Barr, a former Georgia congressman. “The most important question in my mind is would he be better than Hillary Clinton, and the answer is absolutely yes.”

In polls, a majority of voters align with Democrats’ positions on gun control, though political strategists often say that only opponents care passionately enough about the issue to guide their vote. A New York Times/CBS News poll in January found that 57 percent of respondents wanted stricter laws governing gun sales, and 88 percent favored background checks for all purchases.

Mr. Trump goes against that grain. “What we don’t need to do is expand a broken system,” he wrote in his policy paper.

One area in which Mr. Trump does part ways with gun rights activists is on preventing people on the government’s terrorist watch list from buying weapons.

“If somebody is on a watch list and an enemy of state and we know it’s an enemy of state, I would keep them away, absolutely,” he said in an interview with ABC News last year.

Senate Democrats pushed for such a bill, which many of Mr. Trump’s Republican rivals opposed.

As a lifelong resident of New York City, which has some of the strictest gun laws on the books, Mr. Trump is an unlikely supporter of gun rights in a party that usually aligns with the cause because of libertarianism or roots in rural hunting.

In addition to Mr. Trump’s permit to carry a handgun, his two sons are hunters.

Photographs of the two men from a big-game hunting trip in Africa resurfaced last year, stirring criticism from animal rights activists for their poses with exotic animal conquests, including an elephant, a crocodile and a leopard.

At the N.R.A. convention a year ago, Mr. Trump brought out his sons, Eric and Donald Jr.

“These are our people,” Donald Trump Jr. said. “These are things we do on the weekends, in our free time.”

An earlier version of this article misattributed a remark made by a son of Donald J. Trump at a National Rifle Association convention. It was Donald Trump Jr., not Eric Trump, who said: “These are our people. These are things we do on the weekends, in our free time.”

A version of this article appears in print on , on Page A16 of the New York edition with the headline: Trump and Clinton Are Headed for a Clash on Gun Control. Order Reprints | Today’s Paper | Subscribe